User Equipment (UE) typically performs some initial procedures before they can communicate with remote devices over a wireless communications network. Such procedures include, for example, tuning and synchronizing to a Radio Base Station (RBS) in the RAN, and registering with a mobility management entity. Once registered or “attached” to the network, the UE switches between an “IDLE” state and a “CONNECTED” state, as needed, to communicate data. In the IDLE state, the UE remains registered with the network, but is not active—i.e., there is no incoming or outgoing user data to/from the UE. In the CONNECTED state, the UE can exchange user data and signaling with the RBS in the RAN. Once finished transmitting and/or receiving data, the UE moves back to the IDLE state after a predetermined time period of inactivity.
In conventional RAN technologies, the network manages the transitions from the CONNECTED state to the IDLE state for all UEs using a single, manually configured Inactivity Timer. Specifically, after no activity is detected for a given UE for a fixed and pre-defined period of time, the UE is moved to the IDLE state. Inactivity timers are useful because they help ensure that the UEs will not continue to tie up resources they are not currently using. However, such a “global” inactivity timer can also be problematic. For example, configuring an optimized value for the inactivity timer is not straightforward. In many cases, there is often a trade off between the desire for increased radio link capacity and desire to minimize control plane loading. Setting the inactivity timer for too long a value could mean that the existing connections will continue to occupy the same radio resources that were allocated when the connection was initially established. Further, the resources continue to be occupied until the timer expires, even though the UEs have no data or signaling to send or receive. This can greatly impact radio link capacity, which is often measured by the number of simultaneous connected UEs.
On the other hand, setting the inactivity timer for too short a value could mean that the radio resource control (RRC) connections get torn down prematurely. When this occurs, the RRC connections must be quickly re-established very frequently, leading to rapid changes for the UE between the CONNECTED and IDLE states. This behavior may be particularly troublesome in situations where the UEs are running chatty applications, such as messaging. More particularly, such “flip-flop” state transitions can significantly increase the control plane loading due to the frequent connection terminations and re-establishments.
With the ever-increasing penetration of the Smartphone into the market, as well as the numbers and different types of software applications created for such devices, it is getting more difficult to configure a single inactivity timer with a fixed value that is applicable to all subscribers and/or all the time. Conventional RANs have no means to proactively control the state transition of the UEs individually, regardless of the type or kind of applications/services a given UE is using.